The fuel return block generally relates to diesel fuel systems and more specifically to returning diesel fuel to a tank through a common aperture in the tank. The invention relates to the safe withdrawal and return of diesel fuel from tanks upon vehicles and other equipment.
After wagons, transportation companies developed trucks in the last century. Trucks and related vehicles have had various power plants over the decades. In recent decades, diesel engines have become the dominant power source for trucks and related vehicles. The diesel engine has a limited ignition system in comparison to a gasoline engine that has a spark plug on each cylinder to ignite the fuel air mixture for each piston stroke. The diesel engine may have one glow plug that warms diesel fuel for the initial start of the engine. After starting, the diesel engine has a proportionate amount of fuel vaporized and delivered to each cylinder. Each stroke of a piston compresses the diesel fuel vapor in the cylinder until combustion occurs at the top of the piston stroke.
During operations of a truck, the diesel engine runs continuously until stopped by the operator. The continuous operations require a constant flow of fuel from a tank upon the truck. A truck V has a tank T shown adjacent to the chassis ahead of the drive wheels in FIG. 1. Though a tractor is shown, this description applies to other diesel engine powered vehicles. The fuel system of the truck pumps diesel fuel from the tank into the engine's fuel system for combustion. Unlike a gasoline engine that combusts the entire amount of fuel delivered to a cylinder, a diesel engine has fuel not combusted by the engine. The fuel system of the diesel engine continues from the engine back to the tank T. The fuel system returns diesel fuel to the tank under pressure but a different pressure than that of withdrawing fuel from the tank for delivery to the engine. At times, the difference in pressure between withdrawing fuel and returning fuel along with ambient atmospheric pressure leads to cavitations, hammering, or other pumping problems. The pressure difference may also impede venting of the tank causing a risky accumulation of diesel vapors.